Add MachineLoopInfo. This is not yet tested.

llvm-svn: 44384

include/llvm/Analysis/LoopInfo.h

@@ -702,7 +702,7 @@ public:
     LoopBase<BlockT> *L = new LoopBase<BlockT>(BB);
     BBMap[BB] = L;
 
-    BlockT *EntryBlock = &BB->getParent()->getEntryBlock();
+    BlockT *EntryBlock = BB->getParent()->begin();
 
     while (!TodoStack.empty()) {  // Process all the nodes in the loop
       BlockT *X = TodoStack.back();

include/llvm/CodeGen/MachineLoopInfo.h

@@ -0,0 +1,203 @@
+//===- llvm/CodeGen/MachineLoopInfo.h - Natural Loop Calculator -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Owen Anderson and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the MachineLoopInfo class that is used to identify natural 
+// loops and determine the loop depth of various nodes of the CFG.  Note that
+// natural loops may actually be several loops that share the same header node.
+//
+// This analysis calculates the nesting structure of loops in a function.  For
+// each natural loop identified, this analysis identifies natural loops
+// contained entirely within the loop and the basic blocks the make up the loop.
+//
+// It can calculate on the fly various bits of information, for example:
+//
+//  * whether there is a preheader for the loop
+//  * the number of back edges to the header
+//  * whether or not a particular block branches out of the loop
+//  * the successor blocks of the loop
+//  * the loop depth
+//  * the trip count
+//  * etc...
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_MACHINE_LOOP_INFO_H
+#define LLVM_CODEGEN_MACHINE_LOOP_INFO_H
+
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/Analysis/LoopInfo.h"
+
+namespace llvm {
+
+// Provide overrides for Loop methods that don't make sense for machine loops.
+template<>
+PHINode *LoopBase<MachineBasicBlock>::getCanonicalInductionVariable() const {
+  assert(0 && "getCanonicalInductionVariable not supported for machine loops!");
+  return 0;
+}
+
+template<>
+Instruction*
+LoopBase<MachineBasicBlock>::getCanonicalInductionVariableIncrement() const {
+  assert(0 &&
+     "getCanonicalInductionVariableIncrement not supported for machine loops!");
+  return 0;
+}
+
+template<>
+bool LoopBase<MachineBasicBlock>::isLoopInvariant(Value *V) const {
+  assert(0 && "isLoopInvariant not supported for machine loops!");
+  return false;
+}
+
+template<>
+Value *LoopBase<MachineBasicBlock>::getTripCount() const {
+  assert(0 && "getTripCount not supported for machine loops!");
+  return 0;
+}
+
+template<>
+bool LoopBase<MachineBasicBlock>::isLCSSAForm() const {
+  assert(0 && "isLCSSAForm not supported for machine loops");
+  return false;
+}
+
+EXTERN_TEMPLATE_INSTANTIATION(class LoopBase<MachineBasicBlock>);
+EXTERN_TEMPLATE_INSTANTIATION(class LoopInfoBase<MachineBasicBlock>);
+
+typedef LoopBase<MachineBasicBlock> MachineLoop;
+
+class MachineLoopInfo : public MachineFunctionPass {
+  LoopInfoBase<MachineBasicBlock>* LI;
+  friend class LoopBase<MachineBasicBlock>;
+  
+  LoopInfoBase<MachineBasicBlock>& getBase() { return *LI; }
+public:
+  static char ID; // Pass identification, replacement for typeid
+
+  MachineLoopInfo() : MachineFunctionPass(intptr_t(&ID)) {
+    LI = new LoopInfoBase<MachineBasicBlock>();
+  }
+  
+  ~MachineLoopInfo() { delete LI; }
+
+  /// iterator/begin/end - The interface to the top-level loops in the current
+  /// function.
+  ///
+  typedef std::vector<MachineLoop*>::const_iterator iterator;
+  inline iterator begin() const { return LI->begin(); }
+  inline iterator end() const { return LI->end(); }
+
+  /// getLoopFor - Return the inner most loop that BB lives in.  If a basic
+  /// block is in no loop (for example the entry node), null is returned.
+  ///
+  inline MachineLoop *getLoopFor(const MachineBasicBlock *BB) const {
+    return LI->getLoopFor(BB);
+  }
+
+  /// operator[] - same as getLoopFor...
+  ///
+  inline const MachineLoop *operator[](const MachineBasicBlock *BB) const {
+    return LI->getLoopFor(BB);
+  }
+
+  /// getLoopDepth - Return the loop nesting level of the specified block...
+  ///
+  inline unsigned getLoopDepth(const MachineBasicBlock *BB) const {
+    return LI->getLoopDepth(BB);
+  }
+
+  // isLoopHeader - True if the block is a loop header node
+  inline bool isLoopHeader(MachineBasicBlock *BB) const {
+    return LI->isLoopHeader(BB);
+  }
+
+  /// runOnFunction - Calculate the natural loop information.
+  ///
+  virtual bool runOnMachineFunction(MachineFunction &F);
+  
+  bool runOnFunction(Function& F) { return false; }
+
+  virtual void releaseMemory() { LI->releaseMemory(); }
+
+  virtual void print(std::ostream &O, const Module* M = 0) const {
+    if (O) LI->print(O, M);
+  }
+
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+
+  /// removeLoop - This removes the specified top-level loop from this loop info
+  /// object.  The loop is not deleted, as it will presumably be inserted into
+  /// another loop.
+  inline MachineLoop *removeLoop(iterator I) { return LI->removeLoop(I); }
+
+  /// changeLoopFor - Change the top-level loop that contains BB to the
+  /// specified loop.  This should be used by transformations that restructure
+  /// the loop hierarchy tree.
+  inline void changeLoopFor(MachineBasicBlock *BB, MachineLoop *L) {
+    LI->changeLoopFor(BB, L);
+  }
+
+  /// changeTopLevelLoop - Replace the specified loop in the top-level loops
+  /// list with the indicated loop.
+  inline void changeTopLevelLoop(MachineLoop *OldLoop, MachineLoop *NewLoop) {
+    LI->changeTopLevelLoop(OldLoop, NewLoop);
+  }
+
+  /// addTopLevelLoop - This adds the specified loop to the collection of
+  /// top-level loops.
+  inline void addTopLevelLoop(MachineLoop *New) {
+    LI->addTopLevelLoop(New);
+  }
+
+  /// removeBlock - This method completely removes BB from all data structures,
+  /// including all of the Loop objects it is nested in and our mapping from
+  /// MachineBasicBlocks to loops.
+  void removeBlock(MachineBasicBlock *BB) {
+    LI->removeBlock(BB);
+  }
+};
+
+
+// Allow clients to walk the list of nested loops...
+template <> struct GraphTraits<const MachineLoop*> {
+  typedef const MachineLoop NodeType;
+  typedef std::vector<MachineLoop*>::const_iterator ChildIteratorType;
+
+  static NodeType *getEntryNode(const MachineLoop *L) { return L; }
+  static inline ChildIteratorType child_begin(NodeType *N) {
+    return N->begin();
+  }
+  static inline ChildIteratorType child_end(NodeType *N) {
+    return N->end();
+  }
+};
+
+template <> struct GraphTraits<MachineLoop*> {
+  typedef MachineLoop NodeType;
+  typedef std::vector<MachineLoop*>::const_iterator ChildIteratorType;
+
+  static NodeType *getEntryNode(MachineLoop *L) { return L; }
+  static inline ChildIteratorType child_begin(NodeType *N) {
+    return N->begin();
+  }
+  static inline ChildIteratorType child_end(NodeType *N) {
+    return N->end();
+  }
+};
+
+} // End llvm namespace
+
+// Make sure that any clients of this file link in LoopInfo.cpp
+FORCE_DEFINING_FILE_TO_BE_LINKED(MachineLoopInfo)
+
+#endif

lib/CodeGen/MachineLoopInfo.cpp

@@ -0,0 +1,41 @@
+//===- MachineLoopInfo.cpp - Natural Loop Calculator ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Owen Anderson and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the MachineLoopInfo class that is used to identify natural
+// loops and determine the loop depth of various nodes of the CFG.  Note that
+// the loops identified may actually be several natural loops that share the 
+// same header node... not just a single natural loop.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineDominators.h"
+
+using namespace llvm;
+
+TEMPLATE_INSTANTIATION(class LoopBase<MachineBasicBlock>);
+TEMPLATE_INSTANTIATION(class LoopInfoBase<MachineBasicBlock>);
+
+char MachineLoopInfo::ID = 0;
+static RegisterPass<MachineLoopInfo>
+X("machine-loops", "Machine Natural Loop Construction", true);
+
+bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
+  releaseMemory();
+  LI->Calculate(getAnalysis<MachineDominatorTree>().getBase());    // Update
+  return false;
+}
+
+void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesAll();
+  AU.addRequired<MachineDominatorTree>();
+}
+
+// Ensure this file gets linked when MachineLoopInfo.h is used.
+DEFINING_FILE_FOR(MachineLoopInfo)